Question

When asked to find the zeros of the function r(t) = 5t3 – 8t2 + 7t + 2 which task would you complete first - Rational Root Theorem or Descartes’ Rule of Signs? Use complete sentences to explain your reasoning.

Answer 1

Descartes rule of signs, because that will tell you if there are both positive and negative roots. Also it would tell you if there were only positive or only negative which would reduce the possible roots used in rational root theorem.

Answer 2

For example, for r(x) using descartes method we find 0 or 2 positive roots and 1 negative root. Then use rational root theorem to try to factor out a negative root since we know for sure there is 1. try -1,-2